The correct option is A one internode long modified stem capable of photosynthesis
Cladode is an aerial modification of a stem where the stem flattens and forms a leaf like structure. It is one internode long. As flowers are normally present on the stem, here the flowers appear in the middle of the leaf like structures. Also, the true leaves are reduced to scale leaves. E.g. Leaf like structure in Ruscus.
Flower is a specialized reproductive shoot that bears male and female parts of a plant.
Flattened green stem is a type of cladode that has unlimited growth and is known as phylloclade.
Rhizomes are stem modifications that are perennial, fleshy underground stems. These are seen in ginger, banana, turmeric, etc.